1. Field of the Invention
The present invention relates to an automatic door sensor and an automatic door system equipped with the automatic door sensor. In particular, the present invention is related to improving the reliability of door closing actions.
2. Description of the Related Art
As disclosed in Japanese Patent Laid-open Publication No. 2001-152750, etc., an automatic door system equipped with an active infrared sensor is traditionally known in the art. Such an infrared sensor comprises an emitter which projects infrared rays covering a prescribed area and a receiver which receives the infrared rays that are reflected from the infrared coverage area. If a person enters the infrared coverage area, the receiver receives a different pattern of infrared rays, whereupon the sensor thereby recognizes that a person is approaching the automatic door. Based on this recognition, the sensor transmits a detection signal to a door opening/closing mechanism so that a driving source (driving motor) of the automatic door is energized to open the door. After a person leaves the infrared coverage area, the receiver receives infrared rays in the normal pattern again. Then, the sensor discontinues transmitting a detection signal, and as a result, the driving source is energized to close the door.
Many of such active infrared sensors have a timed presence detection capability. Suppose a situation where a person or object has entered the infrared coverage area and remains stationary therein for a certain period of time, namely, where the pattern of infrared rays received by the receiver has changed and does not return to normal after a certain period of time. Under such circumstances, a sensor with the timed presence detection capability forcibly discontinues the transmission of a detection signal, and as a result, the driving source is energized to close the door. This feature effectively avoids a prolonged, unnecessary opening of the door, which is attributable to, for example, a plant or the like that is placed in the infrared coverage area.
In a conventional automatic door, a door member and the opening/closing mechanism of the door member constitute a single complete unit by themselves. In other words, activation of the opening/closing mechanism and consequent opening/closing actions of the door member are solely dependent on whether a detection signal from the sensor is received or not. For the opening/closing actions of the door, the opening speed and the closing speed can be set independently and may be different from each other. To be more specific, the door is closed if the transmission of the detection signal is discontinued due to a person exiting from the infrared coverage area (which is defined herein as xe2x80x9csignal discontinuation due to the exit of an objectxe2x80x9d), or if the transmission of the detection signal is forcibly discontinued due to the continuous presence of a stationary object within the infrared coverage area for a certain period of time (which is defined herein as xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d). In whichever situation, it is conventional to close the door at a relatively high speed.
As mentioned above, provided that the xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d is attributable to a plant or like object that is placed in the infrared coverage area, there is no significant inconvenience in performing a relatively fast closing action at the same speed as in the case of the xe2x80x9csignal discontinuation due to the exit of an objectxe2x80x9d. Nevertheless, a person who stops in the infrared coverage area can also cause the xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d. In this situation, if the door is closed by a relatively fast closing action at the same speed as in the case of xe2x80x9csignal discontinuation due to the exit of an objectxe2x80x9d, a person who, for example, stops around the door rail may not be able to escape from the relatively fast-moving door, which may result in the person being highly in danger of being struck by the door.
The present invention is made in view of the above-identified problem. With regard to an automatic door sensor having a timed presence detection capability, an object of the present invention is to provide an arrangement which is capable of preventing a person from being hit by a closing door when the door closing action results from the xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d.
To achieve this object, the present invention distinguishes between a door closing action resulting from the xe2x80x9csignal discontinuation due to the exit of an objectxe2x80x9d and a door closing action resulting from the xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d. Particularly, the latter closing action is designed in consideration of the presence of a person within the area in such a manner so as to reduce the risk of hitting the person with the door.
Specifically, the present invention relates to an automatic door sensor which sends a door open signal to an automatic door opening/closing mechanism so as to open an automatic door when an object enters a prescribed area around a doorway opening of the automatic door. The automatic door sensor of the present invention also discontinues the transmission of a door open signal to the automatic door opening/closing mechanism so as to close the automatic door by a first closing action when the object leaves the prescribed area. The automatic door sensor is provided with an open/close controller for transmitting a presence detection signal to the automatic door opening/closing mechanism if the object remains stationary within the prescribed area for a certain period of time so as to close the automatic door by a second closing action which is different from the first closing action.
To be more specific, the second closing action resulting from the transmission of a presence detection signal includes the following operations. First, the automatic door is set to close at a reduced speed in comparison with the door closing speed of the first closing action that is to be performed when the object leaves the prescribed area. Second, a vocal warning which gives an advance notice of a closing door is outputted around the doorway opening of the automatic door.
Due to the slow closing action of the automatic door, when the automatic door starts the closing action despite the presence of a person who stops in the area, the person can notice that the door is closing in advance (i.e., before the door hits him/her). Even if the door may hit the person, the slowly closing door will not give a serious impact to the person. Further, a vocal warning that is issued around the doorway opening will also help the person to notice that the door is closing in advance.
Thus, the solution of the present invention distinguishes door closing actions between the one resulting from the xe2x80x9csignal discontinuation due to the exit of an objectxe2x80x9d and the one resulting from the xe2x80x9cforced signal discontinuation in the presence of a stationary objectxe2x80x9d, and an automatic door system of the present invention adopts either door closing action which is suitable for a particular situation.
Furthermore, the automatic door system of the present invention may be composed of an automatic door sensor mentioned in the above-described solution and an automatic door opening/closing mechanism which closes the automatic door by either of the first and second closing actions depending on the status of a signal transmission outputted from the automatic door sensor.